<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>html5 表单的required属性</title>
</head>
<body>
    <!-- 第一步：我们设置两个div -->
    <div class="big_box">
    <div class="box"></div>
    <div class="other"></div>
    </div>
</body>
</html>